not mpg, but gph when just 'on'

If its just for one or two nights you should be okay. In one day, I drove 400 miles and left the car on for about 4 hours to run the air conditioner (it was between 80-95 f) and I got 43.5 mpg. I normally get about 42.5 mpg during a normal 10 days driving. The car seemed to cycle on and off every 20 minutes for I would guess 2-3 minutes each time. I start my car about three time/day at 2 five hour intevals so the car is cold each time. So for an eight hour period you would use less gas than cold starting your car 60 times.

 

I've Heard a Week!

Read this story. I'll bet you can go for at lease days days on a 1,000 watt inverter with a full tank of gas.

The most I've done with my 1,250 watt inverter was 3 hours and I never noticed any fuel gauge or mileage difference.

 

Bob Wilson on the Yahoo Prius_Technical_Stuff group reported 0.16 gallons per hour with an (intermittent?) 800 watt load done this way. Round that up a bit for safety, and realize that it might also increase in very cold conditions because you will get ICE restarts for intake manifold reheating as well as HV battery SOC maintenance. But neither of the batteries will get discharged in this way, assuming that you only use the inverter with Prius in "Ready" mode.

All the Prius inverter users I know have modified sine wave equipment. Given that 1000 watt pure sine wave inverters are sometimes as cheap as $300, I hope someone goes that route someday. Hair dryers and other resistive loads don't care, but some motors and computer equipment are more particular.

 

Okay, here's something that was touched on here, but I think it needs more discussing. This question is for Vincent and anyone else who has actual experience connecting a 1,000W inverter to their Prius.

What is the maximum wattage you have actually drawn? Are you direct off the battery, or through a fuse? If through a 100A fuse, in a perfect world you would be able to draw up to 1,200W. At 90% efficiency 1080W would be available. However, the car needs power too, so even if you are drawing through a separate fuse you could be seriously stressing that little battery.

Curious about what maximum wattages you have actually drawn (is an 800W hair dryer really 'doable' on a routine basis?) and just how you've hooked the inverter up to the battery.

Experiences only -- thanks!

 

I actually did the "hair dryer thing" for my sister-in-law at a campground, and the spec label on it said something below 1000 watts (else I would not have plugged it in). The highest load I have routinely used is a 2-slice toaster, which draws 875 watts. for that, there have been times when the added inverter would alarm and not operate. Those were in desert camping and the inverter was warm and shut down by its own internal thermal limit.

The inverter is installed adjacent to the 12 volt Prius battery, with 6 guage stranded copper wire, lengths less than 18 inches. For longer wire runs, even fatter wire is appropriate. The positive side is spliced to the battery's fat poitive wire.

The added inverter has internal fuses (I suppose this is common) but I am very reluctant to risk blowing the Prius' 100 amp system fuse (expensive, would render the car immobile, and I do not carry a spare). Therefore I added a 100-amp ANL fuse to the positive line. Then, I learned that ANL fuses require something like 1 minute at 20% overcurrent to blow, and downgraded to a 60 amp ANL. This has worked fine with the above loads. If it blows, I only lose my added 110 vac, not vehicle function.

In the classic Prius it is possible to install a conventional household 110 vac double receptacle to the back of the front seat center console (plastic cutting, and careful wiring practice is required). As these receptacles are available in gray, it makes a very attractive installation. Also my model of modified sine wave inverter (mfr = Whistler) has a remote switch that I modified to fit into one of the unused switch positions on lower left dash.

 

Based on 2001-2003 Prius, when the car is "ready" but with no obvious loads, it is taking about 700 watts out of the HV battery. Beyond the inverters and their coolant pump, couldn't tell you where it goes.

At some point he battery state of charge falls to about 52% and the engine lights up. Battery charged up to 55%, engine stops.

If you were, for example, external charging during this, SOC would not fall. But the car would still start from time to time to warm the catalyst . I don't know what sensor it could use to trigger this, other than the engine coolant.

Your estimated 0.1 gallon per hour seems in line with others posted. It would increase with external electrical load. Perhaps not as rapidly as you might think, because of the load mentioned above.